PROJECT SUMMARY There is a paucity of gait training approaches that target specific gait deficits, focus practice preferentially on the paretic leg, and capitalize on motor learning principles to optimize walking. Reduced paretic propulsion during terminal stance is an important post-stroke gait deficit that can negatively impact gait speed, inter-limb symmetry, and walking function. Propulsion can be measured using anterior ground reaction forces (AGRF) recorded from a force platform. We have developed an innovative real-time AGRF biofeedback gait training paradigm for individuals post-stroke that targets propulsive deficits preferentially on the paretic leg. Exciting preliminary data from our laboratory demonstrate that AGRF biofeedback training results in improved push-off, trailing limb angle, and step length from the paretic leg, without concomitant improvements in the non-paretic leg. However, our current gait biofeedback interface is a simple, 2-dimensional, non-engaging display projected on a flat screen. Our objective is to develop a more engaging, motivating, game-based system specifically designed for post-stroke AGRF biofeedback gait training. Our proposal will address a major challenge for rehabilitation clinicians - to make gait training appealing and meaningful so that patients engage in sufficient repetitions, intensity, and challenge to maximize therapeutic effectiveness. ?Gamification? refers to use of video game elements in non-gaming systems (such as rehabilitation) to improve user engagement and shape user behavior, a goal that resonates strongly with rehabilitation clinicians and scientists 6-8. Games provide interactive, real-time, experiential learning facilitated via a computer interface 9. We propose to develop an AGRF biofeedback gait training game that increases patient motivation and engagement while also distracting participants from fatigue or boredom during training. Augmented reality (AR) game-interfaces add virtual characters and visual effects to real-world experiences, while reducing deleterious effects (disorientation, dizziness) often observed in fully-immersive virtual environments. The popular ?Pokemon Go? game (2016), is an example of AR 10,11. Transformative advancements in hardware, virtual and augmented reality, and mobile computing technologies have led to revolutionary new types of computer interfaces for recreational gaming. However, intuitive and engaging games designed specifically for gait retraining are not currently available in rehabilitation clinics. This R21 proposal assembles an investigative team comprised of experts in visual effects and game design, computer science and game-development, and stroke gait rehabilitation to accomplish the following specific aims: (1) To design a visual effects gaming interface that streams in AGRF data as input variable; (2) Synchronize the visual effects gaming-based interface with GRF data recorded during treadmill walking to develop a real-time AGRF biofeedback gait training game, including an augmented reality (AR) game version; (3) To obtain user data from stroke survivors and neuro-rehabilitation clinicians regarding our newly developed real-time AGRF biofeedback gait training game.